From: Brad Fitzpatrick <bradfitz@golang.org>
Date: Thu, 24 Oct 2019 03:54:05 +0000 (-0700)
Subject: syscall: make TestGetdirentries checkptr safe
X-Git-Tag: go1.14beta1~602
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=68981bf309be6143dd4cd769ffa94e9347de1fbb;p=gostls13.git

syscall: make TestGetdirentries checkptr safe

Fixes Darwin.

Updates #35092

Change-Id: I045f070c8549d00610b459e3a82cac870d9ddb54
Reviewed-on: https://go-review.googlesource.com/c/go/+/203077
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
---

diff --git a/src/syscall/getdirentries_test.go b/src/syscall/getdirentries_test.go
index 8505a0bb89..1cbed8d4f7 100644
--- a/src/syscall/getdirentries_test.go
+++ b/src/syscall/getdirentries_test.go
@@ -66,7 +66,15 @@ func testGetdirentries(t *testing.T, count int) {
 		}
 		data := buf[:n]
 		for len(data) > 0 {
-			dirent := (*syscall.Dirent)(unsafe.Pointer(&data[0]))
+			// syscall.Getdirentries's return value may be (and usually is) much
+			// smaller than a syscall.Dirent, which has lots of padding for
+			// the name at the end. The compiler's checkptr validation doesn't like
+			// that. So allocate direntMem that's always big enough, and use that
+			// when converting to *syscall.Dirent.
+			var direntMem [unsafe.Sizeof(syscall.Dirent{})]byte
+			copy(direntMem[:], data)
+			dirent := (*syscall.Dirent)(unsafe.Pointer(&direntMem[0]))
+
 			data = data[dirent.Reclen:]
 			name := make([]byte, dirent.Namlen)
 			for i := 0; i < int(dirent.Namlen); i++ {